Computer sub-lines feeding greater sub-lines feeding even greater sub-lines..... Used to laugh seeing 2 white wheels dropping down left chute while 2 blue ones dropped down other side. Even funnier was seeing a white frontend assy dropping down and being attached to that blue body. Such sights weren't uncommon in a Chev-assy plant in Flint in the 60's.
Yet that final product began life in many different physical areas--but with a masterplan: hence a build sheet? that had to be placed somewhere. That master-sheet prolly was never intended to be a "where-to" guide, but rather a "where-from" history.
Motto must've been "NEVER stop the assy line"; just send it to 'final-finish department' and let them minimize cost to make it presentable! Imagine the guy's redface when he realized that Chevy he bought brand new had been re-painted from the cowl forward!